Golf ball cover composition

ABSTRACT

A durable, injection moldable, thermoplastic elastomer that has the favorable resilience, feel, spin, barrier, and UV stability performance attributes is disclosed herein. An OBC grafted with silane provides a good cover shear durability (cut/tear/abrasion resistance). This invention combines the benefits of OBCs and silane crosslinking technology to yield a golf ball cover with a desirable combination of properties.

CROSS REFERENCES TO RELATED APPLICATIONS

The Present Application is a divisional application of U.S. patentapplication Ser. No. 12/795,427, filed on Jun. 7, 2010, now U.S. Pat.No. 8,795,570 which claims priority to U.S. Provisional PatentApplication No. 61/225,879, filed Jul. 15, 2009, both of which arehereby incorporated by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to golf ball cover compositions. Morespecifically, the present invention relates to golf ball covercompositions composed of a silane crosslinked olefin block copolymer.

2. Description of the Related Art

Traditional golf ball covers have been comprised of balata or blends ofbalata with elastomeric or plastic materials. The traditional balatacovers are relatively soft and flexible. Upon impact, the soft balatacovers compress against the surface of the club producing high spin.Consequently, the soft and flexible balata covers provide an experiencedgolfer with the ability to apply a spin to control the ball in flight inorder to produce a draw or a fade, or a backspin which causes the ballto “bite” or stop abruptly on contact with the green. Moreover, the softbalata covers produce a soft “feel” to the low handicap player. Suchplayability properties (workability, feel, etc.) are particularlyimportant in short iron play with low swing speeds and are exploitedsignificantly by relatively skilled players.

Despite all the benefits of balata, balata covered golf balls are easilycut and/or damaged if mis-hit. Golf balls produced with balata orbalata-containing cover compositions therefore have a relatively shortlife span.

As a result of this negative property, balata and its syntheticsubstitutes, trans-polybutadiene and transpolyisoprene, have beenessentially replaced as the cover materials of choice by other covermaterials such as ionomeric resins and polyurethanes.

Ionomeric resins are polymers containing interchain ionic bonding. As aresult of their toughness, durability and flight characteristics,various ionomeric resins sold by E.I. DuPont de Nemours & Company underthe trademark SURLYN® and by the Exxon Corporation (see U.S. Pat. No.4,911,451) under the trademarks ESCOR® and IOTEK®, have become widelyutilized for the construction of golf ball covers over the traditional“balata” (transpolyisoprene, natural or synthetic) rubbers. As stated,the softer balata covers, although exhibiting enhanced playabilityproperties, lack the durability (cut and abrasion resistance, fatigueendurance, etc.) properties required for repetitive play.

Ionomeric resins are generally ionic copolymers of an olefin, such asethylene, and a metal salt of an unsaturated carboxylic acid, such asacrylic acid, methacrylic acid, or maleic acid. Metal ions, such assodium or zinc, are used to neutralize some portion of the acidic groupsin the copolymer resulting in a thermoplastic elastomer exhibitingenhanced properties, such as durability, for golf ball coverconstruction over balata. However, some of the advantages gained inincreased durability have been offset to some degree by the decreasesproduced in playability. This is because although the ionomeric resinsare very durable, they tend to be very hard when utilized for golf ballcover construction, and thus lack the degree of softness required toimpart the spin necessary to control the ball in flight. Since theionomeric resins are harder than balata, the ionomeric resin covers donot compress as much against the face of the club upon impact, therebyproducing less spin. In addition, the harder and more durable ionomericresins lack the “feel” characteristic associated with the softer balatarelated covers.

As a result, while there are many different commercial grades ofionomers available both from DuPont and Exxon, with a wide range ofproperties which vary according to the type and amount of metal cations,molecular weight, composition of the base resin (for example, relativecontent of ethylene and methacrylic and/or acrylic acid groups) andadditive ingredients such as reinforcement agents, etc., a great deal ofresearch continues in order to develop a golf ball cover compositionexhibiting not only the improved impact resistance and carrying distanceproperties produced by the “hard” ionomeric resins, but also theplayability (for example, “spin”, “feel”, etc.) characteristicspreviously associated with the “soft” balata covers, properties whichare still desired by the more skilled golfer.

Furthermore, a number of different golf ball constructions, such asone-piece, two-piece (a solid resilient center or core with a moldedcover), three-piece (a liquid or solid center, elastomeric winding aboutthe center, and a molded cover), and multi-piece golf balls, have beendeveloped to produce golf balls exhibiting enhanced playability anddurability. The different types of materials utilized to formulate thecores, mantles, windings, covers, etc. of these balls dramaticallyalters the balls' overall characteristics. In addition, multi-layeredcovers containing one or more ionomer resins or other materials havealso been formulated in an attempt to produce a golf ball having theoverall distance, playability and durability characteristics desired.

For example, in various attempts to produce a durable, high spin golfball, the golfing industry has blended the hard ionomer resins with anumber of softer ionomeric resins and applied these blends to two-pieceand three-piece golf balls. U.S. Pat. Nos. 4,884,814 and 5,120,791 aredirected to cover compositions containing blends of hard and softionomeric resins. However, it has been found that golf ball coversformed from hard-soft ionomer blends tend to become scuffed more readilythan covers made of hard ionomer alone. Consequently, it would be usefulto develop a golf ball having a combination of softness and durabilitywhich is better than the softness-durability combination of a golf ballcover made from a hard-soft ionomer blend.

Additionally, thermoset and thermoplastic polyurethanes have recentlybecome popular materials of choice for golf ball cover construction.However, these polyurethanes are difficult and time consuming toprocess. Moreover, the molding of relatively thin wall cover layer(s),i.e., cover layers 0.075 inch or less in cross-sectional thickness, isdifficult to accomplish. This limits the desired performance achieved bythin wall cover molding, such as improved distance. Furthermore, golfballs produced utilizing these materials tend to be soft and readilysusceptible to scuffing.

Solid golf ball covers are typically composed of ionomer or polyurethanematerials. While ionomer covers can provide good durability andresilience, they also exhibit a “hard” feel and lower spin rates.Polyurethane covers can be made to exhibit good durability, “soft” feel,and high spin rates. However, they typically have inferior resilience,poor barrier properties to moisture, and poor UV stability. Therefore,there remains a need for a golf ball cover material that exhibits gooddurability, high resilience, “soft” feel, high spin rates, good moisturebarrier properties, and good UV stability.

U.S. Pat. No. 7,279,529 describes the use of polyethylene and othermetallocene based polyolefins paired with silane crosslinking technologyto produce golf ball layers. However, the polyolefins disclosed in thePatent do not have ideal elastomeric properties and do not provide adurable, resilient golf ball cover in conjunction with desirable feeland spin.

Thus, there is a need for a durable golf ball cover composed of a newmaterial.

BRIEF SUMMARY OF THE INVENTION

The present invention seeks to overcome the prior art problems with theuse of a new class of olefinic thermoplastic elastomers called olefinblock copolymers (“OBC”). The use of these ordered OBC materials withsilane crosslinking technology produces golf ball cover materials withimproved durability, resilience, feel, spin, barrier properties, and UVstability.

The major goal of this project is to provide a durable, injectionmoldable, thermoplastic elastomer that has the favorable resilience,feel, spin, barrier, and UV stability performance attributes notedabove. An OBC (e.g. Dow's INFUSE ethylene-octene block copolymer) canprovide these attributes except for durability. To achieve good covershear durability (cut/tear/abrasion resistance), silane crosslinking isa must. This invention combines the benefits of OBCs and silanecrosslinking technology to yield a golf ball cover with a desirablecombination of properties.

It is an objective to utilize the combination of OBCs with silanecrosslinking technology to produce polyolefin based golf ball coverswith improved durability, resilience, feel and spin.

Having briefly described the present invention, the above and furtherobjects, features and advantages thereof will be recognized by thoseskilled in the pertinent art from the following detailed description ofthe invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a golf ball 8 embodying theinvention illustrating a core 10 and a cover 12 consisting of an innerlayer 14 and an outer layer 16.

FIG. 2 is a diametrical cross-sectional view of a golf ball 8 of theinvention having a core 10 and a cover 12 made of an inner layer 14 andan outer layer 16.

FIG. 3 is a cross-sectional view of a golf ball 8 embodying theinvention illustrating a dual core having an inner core 20 and a corelayer 22, and a cover 12 consisting of an inner layer 14 and an outerlayer 16.

FIG. 4 is an illustration of a process for grafting of vinyl-silanesonto OBC.

FIG. 5 is an illustration of a process for moisture crosslinking ofsilane grafted OBC.

FIG. 6 is a table of compound compositions including a compound of acomposition of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

A process for grafting of vinyl-silanes onto OBC is shown in FIG. 4, anda process for moisture crosslinking of silane grafted OBC is shown inFIG. 5. Step one involves radical formation of a peroxide into a freeradicals using heat. Step two involves grafting a silane onto an OBC tocreate a silane grafted OBC. Step three involves hydrolysis of thesilane grafted OBC. Step four involves condensation to create a silancrosslinked OBC.

In this process, vinylsilane (e.g. trimethoxyvinylsilane) is firstgrafted onto the OBC. This is done in a compounding process where theOBC and silane are added along with a free radical generator (dicumylperoxide) to a twin screw extruder. The silane grafted OBC is then dryblended with a tin catalyst masterbatch and injection molded. Afterinjection molding, the part is moisture cured in a hot water bath toimpart the final crosslinking. Water in combination with the tincatalyst and heat hydrolyzes the alkoxysilane moieties on the silanethat in turn condenses to form siloxane crosslinks. This process issimilar to the PEX (crosslinked polyethylene) Monosil/Sioplas processesand has the advantage that crosslinking doesn't occur until afterprocessing. The crosslinking improves durability of the golf ball cover.

In one aspect, the present invention provides a golf ball comprising acore, a hard inner cover layer formed over the core, and a softer outercover layer formed over the inner cover layer. The inner cover layer hasa Shore D hardness of at least 60 (or at least about 80 Shore C) asmeasured on the curved surface thereof and is formed of a compositionincluding at least one material selected from the group of consisting ofionomers, polyamides, polyurethanes, polyureas, polyester elastomers,polyester amides, metallocene catalyzed polyolefins, and blends thereof.The outer cover layer has a Shore D hardness of less than 60, preferablya Shore D hardness of 55 or less, more preferably 50 or less, and mostpreferably 45 or less as measured on the curved surface thereof.

The mantle layer is preferably composed of a HPF material available fromDuPont. Alternatively, the mantle layer is composed of a material suchas disclosed in Kennedy, III et al., U.S. Pat. No. 7,361,101 for a GolfBall And Thermoplastic Material, which is hereby incorporated byreference in its entirety.

The golf ball preferably has an aerodynamic pattern such as disclosed inSimonds et al., U.S. Pat. No. 7,419,443 for a Low Volume Cover For AGolf Ball, which is hereby incorporated by reference in its entirety.Alternatively, the golf ball has an aerodynamic pattern such asdisclosed in Simonds et al., U.S. Pat. No. 7,338,392 for An AerodynamicSurface Geometry For A Golf Ball, which is hereby incorporated byreference in its entirety. Alternatively, the golf ball has anaerodynamic pattern such as disclosed in Simonds et al., U.S. Pat. No.7,468,007 for a Dual Dimple Surface Geometry For A Golf Ball, which ishereby incorporated by reference in its entirety.

In reference to FIGS. 1-3, the present invention relates to improvedmulti-layer golf balls, particularly a golf ball 8 comprising amulti-layered cover 12 over a solid core 10, and method for making same.The golf balls of the invention can be of a standard or enlarged size,and the outer cover layer has improved scuff resistance. The core mayhave multiple layers, such as a dual core as shown in FIG. 3 having aspherical center or inner core 20 and a core layer 22 surrounding theinner core. Additional core layers may also be present. The cover layeris preferably a multi-layer cover comprising at least an inner coverlayer and an outer cover, although any number of cover layers, such as2, 3, 4, 5 or more is possible.

The core 10, or the dual core 20, 22, of the golf ball can be formed ofa solid, a liquid, or any other substance that will result in an innerball (core and inner cover layer), having the desired COR, compressionand hardness. The multi-layered cover 12 comprises two layers: a firstor inner layer or ply 14 and a second or outer layer or ply 16. Theinner layer 14 can be ionomer, ionomer blends, non-ionomer, non-ionomerblends, or blends of ionomer and non-ionomer. The outer layer 16 ispreferably softer than the inner layer and can be polyurethane,polyurea, polyurethane/polyurea blends, or a blend of apolyurethane/polyurea and ionomer or non-ionomer.

In a further embodiment, the inner layer 14 is comprised of a hard, highacid (i.e. greater than 16 weight percent acid) ionomer resin or highacid ionomer blend. Preferably, the inner layer is comprised of a blendof two or more high acid (i.e. at least 16 weight percent acid) ionomerresins neutralized to various extents by different metal cations. Theinner cover layer may or may not include a metal stearate (e.g., zincstearate) or other metal fatty acid salt. The purpose of the metalstearate or other metal fatty acid salt is to lower the cost ofproduction without affecting the overall performance of the finishedgolf ball. In an additional embodiment, the inner layer 14 is comprisedof a hard, low acid (i.e. 16 weight percent acid or less) ionomer blend.Preferably, the inner layer is comprised of a blend of two or more lowacid (i.e. 16 weight percent acid or less) ionomer resins neutralized tovarious extents by different metal cations. The inner cover layer may ormay not include a metal stearate (e.g., zinc stearate) or other metalfatty acid salt.

It has been found that a hard inner layer provides for a substantialincrease in resilience (i.e., enhanced distance) over known multi-layercovered balls. The softer outer layer provides for desirable “feel” andhigh spin rate while maintaining respectable resiliency. The soft outerlayer allows the cover to deform more during impact and increases thearea of contact between the clubface and the cover, thereby impartingmore spin on the ball. As a result, the soft cover provides the ballwith a balata-like feel and playability characteristics with improveddistance and durability. Consequently, the overall combination of theinner and outer cover layers results in a golf ball having enhancedresilience (improved travel distance) and durability (i.e. cutresistance, etc.) characteristics while maintaining and in manyinstances, improving, the playability properties of the ball.

Preferably, the inner cover layer is harder than the outer cover layerand generally has a thickness in the range of 0.010 to 0.150 inch,preferably 0.010-0.100 inch, more preferably 0.020 to 0.060 inch for a1.68 inch ball and 0.030 to 0.100 inch for a 1.72 inches (or more) ball.The core and inner cover layer together form an inner ball having acoefficient of restitution of 0.780 or more and more preferably 0.790 ormore, and a diameter in the range of 1.48 to 1.67 inches for a 1.68 inchball and 1.50 to 1.71 inches for a 1.72 inch (or more) ball. The innercover layer has a Shore D hardness of 60 or more (or at least about 80Shore C). It is particularly advantageous if the golf balls of theinvention have an inner layer with a Shore D hardness of 65 or more (orat least about 100 Shore C). If the inner layer is too thin, it is verydifficult to accurately measure the Shore D, and sometimes the Shore C,of the inner layer as the layer may puncture. Additionally, if the coreis harder, this will sometimes influence the reading. If the Shore C orShore D is measured on a plaque of material, different values willresult. The above-described characteristics of the inner cover layerprovide an inner ball having a PGA compression of 100 or less. It isfound that when the inner ball has a PGA compression of 90 or less,excellent playability results.

The inner layer compositions of the embodiments described herein mayinclude the high acid ionomers such as those developed by E.I. DuPont deNemours & Company under the trademark Surlyn® and by Exxon Corporationunder the trademarks Escor® or Iotek®, or blends thereof. Examples ofthe high acid methacrylic acid based ionomers found suitable for use inaccordance with this invention include Surlyn® 8220 and 8240 (bothformerly known as forms of Surlyn® AD-8422), Surlyn® 9220 (zinc cation),Surlyn® SEP-503-1 (zinc cation), and Surlyn® SEP-503-2 (magnesiumcation). According to DuPont, all of these ionomers contain from about18.5 to about 21.5% by weight methacrylic acid. Examples of the highacid acrylic acid based ionomers suitable for use in the presentinvention also include the Escor® or Iotek® high acid ethylene acrylicacid ionomers produced by Exxon such as Ex 1001, 1002, 959, 960, 989,990, 1003, 1004, 993, 994. In this regard, Escor® or Iotek® 959 is asodium ion neutralized ethylene-acrylic neutralized ethylene-acrylicacid copolymer. According to Exxon, Ioteks® 959 and 960 contain fromabout 19.0 to about 21.0% by weight acrylic acid with approximately 30to about 70 percent of the acid groups neutralized with sodium and zincions, respectively.

The outer layer is 0.005 to about 0.150 inch in thickness, preferably0.010 to 0.075 inch in thickness, more desirably 0.015 to 0.050 inch inthickness, but thick enough to achieve desired playabilitycharacteristics while minimizing expense. Thickness is defined as theaverage thickness of the non-dimpled areas of the outer cover layer. Theouter cover layer 16 has a Shore D hardness of less than 60 (or lessthan about 90 Shore C), and more preferably 55 or less (or about 85 to88 Shore C or less). If the outer layer is too thin, it is verydifficult to accurately measure the Shore D, and sometimes the Shore C,of the outer layer as the layer may puncture. Additionally, if the innerlayer and/or core is harder than the outer layer, this will sometimesinfluence the reading. If the Shore C or Shore D is measured on a plaqueof material, different values may result.

The outer cover layer of the invention is formed over a core to resultin a golf ball having a coefficient of restitution of at least 0.770,more preferably at least 0.780, and most preferably at least 0.790. Thecoefficient of restitution of the ball will depend upon the propertiesof both the core and the cover. The PGA compression of the golf ball is100 or less, and preferably is 90 or less.

The cores of the inventive golf balls typically have a coefficient ofrestitution of about 0.750 or more, more preferably 0.770 or more and aPGA compression of about 90 or less, and more preferably 70 or less.Furthermore, in some applications it may be desirable to provide a corewith a coefficient of restitution of about 0.780 to 0.790 or more. Thecore used in the golf ball of the invention preferably is a solid. Theterm “solid cores” as used herein refers not only to one piece cores butalso to those cores having a separate solid layer beneath the covers andover the central core. The cores have a weight of 25-40 grams andpreferably 30-40 grams. When the golf ball of the invention has a solidcore, this core can be compression molded from a slug of uncured orlightly cured elastomer composition comprising a high cis contentpolybutadiene and a metal salt of an α, β, ethylenically unsaturatedcarboxylic acid such as zinc mono- or diacrylate or methacrylate. Toachieve higher coefficients of restitution and/or to increase hardnessin the core, the manufacturer may include a small amount of a metaloxide such as zinc oxide. In addition, larger amounts of metal oxidethan are needed to achieve the desired coefficient may be included inorder to increase the core weight so that the finished ball more closelyapproaches the U.S.G.A. upper weight limit of 1.620 ounces. Non-limitingexamples of other materials which may be used in the core compositionincluding compatible rubbers or ionomers, and low molecular weight fattyacids such as stearic acid. Free radical initiator catalysts such asperoxides are admixed with the core composition so that on theapplication of heat and pressure, a curing or cross-linking reactiontakes place.

A thread wound core may comprise a liquid, solid, gel or multi-piececenter. The thread wound core is typically obtained by winding a threadof natural or synthetic rubber, or thermoplastic or thermosettingelastomer such as polyurethane, polyester, polyamide, etc. on a solid,liquid, gel or gas filled center to form a thread rubber layer that isthen covered with one or more mantle or cover layers. Additionally,prior to applying the cover layers, the thread wound core may be furthertreated or coated with an adhesive layer, protective layer, or anysubstance that may improve the integrity of the wound core duringapplication of the cover layers and ultimately in usage as a golf ball.

In preparing golf balls in accordance with the present invention, aninner cover layer, preferably a hard inner cover layer, is molded (forexample, by injection molding or by compression molding) about a core(preferably a solid core). A comparatively softer outer layer is molded(for example, by injection molding or by reaction injection molding)over the inner layer.

The solid core for the multi-layer ball is about 1.2 to 1.6 inches indiameter, although it may be possible to use cores in the range of about1.0 to 2.0 inches. Conventional solid cores are typically compression orinjection molded from a slug or ribbon of uncured or lightly curedelastomer composition comprising a high cis content polybutadiene and ametal salt of an α, β, ethylenically unsaturated carboxylic acid such aszinc mono or diacrylate or methacrylate. To achieve higher coefficientsof restitution in the core, the manufacturer may include fillers such assmall amounts of a metal oxide such as zinc oxide. In addition, largeramounts of metal oxide than those that are needed to achieve the desiredcoefficient are often included in conventional cores in order toincrease the core weight so that the finished ball more closelyapproaches the U.S.G.A. upper weight limit of 1.620 ounces. Othermaterials may be used in the core composition including compatiblerubbers or ionomers, and low molecular weight fatty acids such asstearic acid. Free radical initiators such as peroxides are admixed withthe core composition so that on the application of heat and pressure, acomplex curing cross-linking reaction takes place.

In some embodiments, the inner cover layer(s) that is molded over thecore is about 0.010 inch to about 0.150 inch in thickness, morepreferably about 0.020 to about 0.10 inch thick. The inner ball thatincludes the core and inner cover layer(s) preferably has a diameter inthe range of 1.25 to 1.64 inches. The outer cover layer is 0.005 inch to0.075 inch in thickness, preferably 0.010 to 0.050 inch thick, morepreferably 0.010 to 0.040 inch thick, and most preferably 0.010 to 0.030inch thick. Together, the core, the inner cover layer(s) and the outercover layer combine to form a ball having a diameter of 1.680 inches ormore, the minimum diameter permitted by the rules of the United StatesGolf Association and weighing no more than 1.62 ounces.

In an alternative embodiment of the invention, the golf ball has adimple pattern that provides dimple coverage of 65% or more, preferably75% or more, and more preferably 85% or more. In a preferred embodimentof the invention, there are greater than 300 dimples, preferably fromabout 300 to about 500 dimples.

In a preferred embodiment, the golf ball typically is coated with adurable, abrasion-resistant, relatively non-yellowing finish coat orcoats if necessary. The finish coat or coats may have some opticalbrightener added to improve the brightness of the finished golf ball. Ina preferred embodiment, from 0.001 to about 10% optical brightener maybe added to one or more of the finish coatings. Preferred finishcoatings are solvent based urethane coatings known in the art.

The golf balls of the present invention can be produced by moldingprocesses, which include but are not limited to those that are currentlywell known in the golf ball art. For example, the golf balls can beproduced by injection molding or compression molding the novel covercompositions around a wound or solid molded core to produce an innerball, which typically has a diameter of about 1.50 to 1.67 inches. Theouter layer is subsequently molded over the inner layer to produce agolf ball having a diameter of about 1.680 inches or more. Althougheither solid cores or wound cores can be used in the present invention,as a result of their lower cost and superior performance, solid moldedcores are preferred over wound cores. The standards for both the minimumdiameter and maximum weight of the balls are established by the UnitedStates Golf Association (U.S.G.A.).

In compression molding, the inner cover composition is formed viainjection molding at about 380° F. to about 450° F. into smooth surfacedhemispherical shells which are then positioned around the core in a moldhaving the desired inner cover thickness and subjected to compressionmolding at 200° F. to 300° F. for about 2 to 10 minutes, followed bycooling at 50° F. to 70° F. for about 2 to 7 minutes to fuse the shellstogether to form a unitary intermediate ball. In addition, theintermediate balls may be produced by injection molding wherein theinner cover layer is injected directly around the core placed at thecenter of an intermediate ball mold for a period of time in a moldtemperature of from 50° F. to about 100° F. Subsequently, the outercover layer is molded about the core and the inner layer by similarmolding techniques to form a dimpled golf ball of a diameter of 1.680inches or more. To improve the adhesion between the inner cover layerand the outer cover layer, an adhesion promoter may be used. Someadhesion promoters, such as abrasion of the surface, corona treatment,and the like, are known in the art. A preferred adhesion promoter is achemical adhesion promoter, such as a silane or other silicon compound,preferably N-(2-aminoethyl)3-aminopropyltrimethoxysilane. Theintermediate golf ball (core and inner cover layer) may be dipped orsprayed with the chemical, and then the outer cover layer is formed overthe treated inner cover layer.

After molding, the golf balls produced may undergo various furtherprocessing steps such as buffing, painting and marking as disclosed inU.S. Pat. No. 4,911,451.

From the foregoing it is believed that those skilled in the pertinentart will recognize the meritorious advancement of this invention andwill readily understand that while the present invention has beendescribed in association with a preferred embodiment thereof, and otherembodiments illustrated in the accompanying drawings, numerous changes,modifications and substitutions of equivalents may be made thereinwithout departing from the spirit and scope of this invention which isintended to be unlimited by the foregoing except as may appear in thefollowing appended claims. Therefore, the embodiments of the inventionin which an exclusive property or privilege is claimed are defined inthe following appended claims.

We claim as our invention the following:
 1. A golf ball comprising: acover layer formed from crosslinked silane grafted ethylene-octene blockcopolymer material, wherein the crosslinked silane grafted olefin blockcopolymer material comprises 99 parts olefin block copolymer and 1 partsilane.
 2. The golf ball according to claim 1 further comprising a coreand a mantle layer.
 3. The golf ball according to claim 1 furthercomprising a dual core and a mantle layer.
 4. The golf ball according toclaim 1 further comprising a core.
 5. The golf ball according to claim 1further comprising a core and a mantle layer composed of a HPF material.6. The golf ball according to claim 1 further comprising a thread woundcore and a mantle layer.
 7. The golf ball according to claim 1 whereinthe cover has a thickness ranging from 0.020 inch to 0.150 inch, and thegolf ball has a diameter of 1.68 inches.
 8. The golf ball according toclaim 1 wherein the cover has a Shore D hardness ranging from 30 to 70.